From: Sean Young Date: Fri, 26 Oct 2018 12:18:33 +0000 (-0400) Subject: media: v4l uapi docs: few minor corrections and typos X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=2e9a2ec53cd6e93b5b7f6d15a4cc6bdb4ba82488;p=openwrt%2Fstaging%2Fblogic.git media: v4l uapi docs: few minor corrections and typos Do a series of minor corrections at the V4L2 uAPI documentation. Signed-off-by: Sean Young Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- diff --git a/Documentation/media/uapi/v4l/app-pri.rst b/Documentation/media/uapi/v4l/app-pri.rst index a8c41a7ec396..e03929ebe899 100644 --- a/Documentation/media/uapi/v4l/app-pri.rst +++ b/Documentation/media/uapi/v4l/app-pri.rst @@ -8,7 +8,7 @@ Application Priority When multiple applications share a device it may be desirable to assign them different priorities. Contrary to the traditional "rm -rf /" school -of thought a video recording application could for example block other +of thought, a video recording application could for example block other applications from changing video controls or switching the current TV channel. Another objective is to permit low priority applications working in background, which can be preempted by user controlled diff --git a/Documentation/media/uapi/v4l/audio.rst b/Documentation/media/uapi/v4l/audio.rst index 5ec99a2809fe..725a61b59cb1 100644 --- a/Documentation/media/uapi/v4l/audio.rst +++ b/Documentation/media/uapi/v4l/audio.rst @@ -31,7 +31,7 @@ outputs applications can enumerate them with the :ref:`VIDIOC_ENUMAUDOUT ` ioctl, respectively. The struct :c:type:`v4l2_audio` returned by the :ref:`VIDIOC_ENUMAUDIO` ioctl also contains signal -:status information applicable when the current audio input is queried. +status information applicable when the current audio input is queried. The :ref:`VIDIOC_G_AUDIO ` and :ref:`VIDIOC_G_AUDOUT ` ioctls report the current diff --git a/Documentation/media/uapi/v4l/dev-capture.rst b/Documentation/media/uapi/v4l/dev-capture.rst index 4218742ab5d9..09949ac54be4 100644 --- a/Documentation/media/uapi/v4l/dev-capture.rst +++ b/Documentation/media/uapi/v4l/dev-capture.rst @@ -99,6 +99,6 @@ requests and always returns default parameters as :ref:`VIDIOC_G_FMT ` +A video capture device may support the :ref:`read() function ` and/or streaming (:ref:`memory mapping ` or :ref:`user pointer `) I/O. See :ref:`io` for details. diff --git a/Documentation/media/uapi/v4l/dev-teletext.rst b/Documentation/media/uapi/v4l/dev-teletext.rst index 2648f6b37ea3..436c7393759a 100644 --- a/Documentation/media/uapi/v4l/dev-teletext.rst +++ b/Documentation/media/uapi/v4l/dev-teletext.rst @@ -10,7 +10,7 @@ This interface was aimed at devices receiving and demodulating Teletext data [:ref:`ets300706`, :ref:`itu653`], evaluating the Teletext packages and storing formatted pages in cache memory. Such devices are usually implemented as microcontrollers with serial interface -(I:sup:`2`\ C) and could be found on old TV cards, dedicated Teletext +(I\ :sup:`2`\ C) and could be found on old TV cards, dedicated Teletext decoding cards and home-brew devices connected to the PC parallel port. The Teletext API was designed by Martin Buck. It was defined in the diff --git a/Documentation/media/uapi/v4l/format.rst b/Documentation/media/uapi/v4l/format.rst index 3e3efb0e349e..dc8ccd8bf982 100644 --- a/Documentation/media/uapi/v4l/format.rst +++ b/Documentation/media/uapi/v4l/format.rst @@ -12,7 +12,7 @@ Data Format Negotiation Different devices exchange different kinds of data with applications, for example video images, raw or sliced VBI data, RDS datagrams. Even -within one kind many different formats are possible, in particular an +within one kind many different formats are possible, in particular there is an abundance of image formats. Although drivers must provide a default and the selection persists across closing and reopening a device, applications should always negotiate a data format before engaging in diff --git a/Documentation/media/uapi/v4l/mmap.rst b/Documentation/media/uapi/v4l/mmap.rst index 670596c1a4f7..0f0968799e69 100644 --- a/Documentation/media/uapi/v4l/mmap.rst +++ b/Documentation/media/uapi/v4l/mmap.rst @@ -231,17 +231,17 @@ up the output is started with :ref:`VIDIOC_STREAMON `. In the write loop, when the application runs out of free buffers, it must wait until an empty buffer can be dequeued and reused. -To enqueue and dequeue a buffer applications use the :ref:`VIDIOC_QBUF` -and :ref:`VIDIOC_DQBUF ` ioctl. The status of a buffer -being mapped, enqueued, full or empty can be determined at any time -using the :ref:`VIDIOC_QUERYBUF` ioctl. Two methods exist to suspend -execution of the application until one or more buffers can be dequeued. -By default :ref:`VIDIOC_DQBUF ` blocks when no buffer is -in the outgoing queue. When the ``O_NONBLOCK`` flag was given to the -:ref:`open() ` function, :ref:`VIDIOC_DQBUF ` -returns immediately with an ``EAGAIN`` error code when no buffer is -available. The :ref:`select() ` or :ref:`poll() -` functions are always available. +To enqueue and dequeue a buffer applications use the +:ref:`VIVIOC_QBUF ` and :ref:`VIDIOC_DQBUF ` +ioctl. The status of a buffer being mapped, enqueued, full or empty can +be determined at any time using the :ref:`VIDIOC_QUERYBUF` ioctl. Two +methods exist to suspend execution of the application until one or more +buffers can be dequeued. By default :ref:`VIDIOC_DQBUF ` +blocks when no buffer is in the outgoing queue. When the ``O_NONBLOCK`` +flag was given to the :ref:`open() ` function, +:ref:`VIDIOC_DQBUF ` returns immediately with an ``EAGAIN`` +error code when no buffer is available. The :ref:`select() ` +or :ref:`poll() ` functions are always available. To start and stop capturing or output applications call the :ref:`VIDIOC_STREAMON ` and :ref:`VIDIOC_STREAMOFF diff --git a/Documentation/media/uapi/v4l/open.rst b/Documentation/media/uapi/v4l/open.rst index afd116edb40d..251a788d80f1 100644 --- a/Documentation/media/uapi/v4l/open.rst +++ b/Documentation/media/uapi/v4l/open.rst @@ -53,7 +53,7 @@ ranges. These ranges are listed in :ref:`devices`. The creation of character special files (with mknod) is a privileged operation and devices cannot be opened by major and minor number. That -means applications cannot *reliable* scan for loaded or installed +means applications cannot *reliably* scan for loaded or installed drivers. The user must enter a device name, or the application can try the conventional device names. diff --git a/Documentation/media/uapi/v4l/tuner.rst b/Documentation/media/uapi/v4l/tuner.rst index ad117b068831..178a0aea4d3a 100644 --- a/Documentation/media/uapi/v4l/tuner.rst +++ b/Documentation/media/uapi/v4l/tuner.rst @@ -31,7 +31,7 @@ current video or radio input is queried. .. note:: :ref:`VIDIOC_S_TUNER ` does not switch the - current tuner, when there is more than one at all. The tuner is solely + current tuner, when there is more than one. The tuner is solely determined by the current video input. Drivers must support both ioctls and set the ``V4L2_CAP_TUNER`` flag in the struct :c:type:`v4l2_capability` returned by the :ref:`VIDIOC_QUERYCAP` ioctl when the @@ -41,7 +41,7 @@ current video or radio input is queried. Modulators ========== -Video output devices can have one or more modulators, uh, modulating a +Video output devices can have one or more modulators, that modulate a video signal for radiation or connection to the antenna input of a TV set or video recorder. Each modulator is associated with one or more video outputs, depending on the number of RF connectors on the diff --git a/Documentation/media/uapi/v4l/userp.rst b/Documentation/media/uapi/v4l/userp.rst index dc2893a60d65..e25715a2c6fa 100644 --- a/Documentation/media/uapi/v4l/userp.rst +++ b/Documentation/media/uapi/v4l/userp.rst @@ -62,9 +62,9 @@ memory pages at any time between the completion of the DMA and this ioctl. The memory is also unlocked when :ref:`VIDIOC_STREAMOFF ` is called, :ref:`VIDIOC_REQBUFS`, or when the device is closed. -Applications must take care not to free buffers without dequeuing. For -once, the buffers remain locked until further, wasting physical memory. -Second the driver will not be notified when the memory is returned to +Applications must take care not to free buffers without dequeuing. +Firstly, the buffers remain locked for longer, wasting physical memory. +Secondly the driver will not be notified when the memory is returned to the application's free list and subsequently reused for other purposes, possibly completing the requested DMA and overwriting valuable data. @@ -90,7 +90,7 @@ To start and stop capturing or output applications call the .. note:: - ref:`VIDIOC_STREAMOFF ` removes all buffers from + :ref:`VIDIOC_STREAMOFF ` removes all buffers from both queues and unlocks all buffers as a side effect. Since there is no notion of doing anything "now" on a multitasking system, if an application needs to synchronize with another event it should examine diff --git a/Documentation/media/uapi/v4l/video.rst b/Documentation/media/uapi/v4l/video.rst index d2bc06b064ad..054af871c217 100644 --- a/Documentation/media/uapi/v4l/video.rst +++ b/Documentation/media/uapi/v4l/video.rst @@ -7,7 +7,7 @@ Video Inputs and Outputs ************************ Video inputs and outputs are physical connectors of a device. These can -be for example RF connectors (antenna/cable), CVBS a.k.a. Composite +be for example: RF connectors (antenna/cable), CVBS a.k.a. Composite Video, S-Video and RGB connectors. Camera sensors are also considered to be a video input. Video and VBI capture devices have inputs. Video and VBI output devices have outputs, at least one each. Radio devices have @@ -19,7 +19,7 @@ outputs applications can enumerate them with the :ref:`VIDIOC_ENUMOUTPUT` ioctl, respectively. The struct :c:type:`v4l2_input` returned by the :ref:`VIDIOC_ENUMINPUT` ioctl also contains signal -:status information applicable when the current video input is queried. +status information applicable when the current video input is queried. The :ref:`VIDIOC_G_INPUT ` and :ref:`VIDIOC_G_OUTPUT ` ioctls return the index of